Inhibitory effects and molecular mechanisms of tetrahydrocurcumin against human breast cancer MCF-7 cells

The Role of Tetrahydrocurcumin in Tumor and Neurodegenerative Diseases Through Anti-Inflammatory Effects

Tetrahydrocurcumin (THC), a curcumin derivative, shows potential in oncology and neurology. It regulates NF-κB, reduces inflammation, promotes cancer cell apoptosis, inhibits tumor angiogenesis, and enhances antioxidants, aiding in treating inflammation-related cancers. In neurology, THC's anti-inflammatory and antioxidant properties protect neurons, reduce neuroinflammation, and support autophagy for cellular debris clearance, with its blood-brain barrier penetration offering a neuroprotective edge. Research on THC's therapeutic application must focus on improving delivery and bioavailability and confirming its clinical safety and efficacy.

Prominent Naturally Derived Oxidative-Stress-Targeting Drugs and Their Applications in Cancer Treatment

The relationship between oxidative stress and cancer has been extensively studied and highlighted, along with its role in various aspects of angiogenesis. The modulation of oxidative levels and the adaptive mechanisms of oxidative stress in cancer systems are attractive research themes for developing anti-cancer strategies. Reactive oxygen species (ROS) are involved in various pathophysiological processes and play crucial roles in DNA damage and angiogenesis. Although cancer cells have developed various adaptive defense mechanisms against oxidative stress, excessive ROS production has been proposed as an anti-cancer strategy to induce cellular apoptosis. In particular, natural-source-based antioxidants have been identified as effective against cancers, and various delivery platforms have been developed to enhance their efficacy. In this review, we highlighted the anti-cancer components (plumbagin, quercetin, resveratrol, curcumin, xanthatin, carvacrol, telmisartan, and sulforaphane) that modulate ROS levels and the recent targeting platforms used to increase the application of anti-cancer drugs and the developed delivery platforms with diverse mechanisms of action. Further, we summarized the actual doses used and the effects of these drug candidates in various cancer systems. Overall, this review provides beneficial research themes for expanding cancer-targeting fields and addressing limited applications in diverse cancer types.

The anticancer potential of tetrahydrocurcumin-phytosomes against oral carcinoma progression

BACKGROUND

Herbal medicine combined with nanotechnology offers an alternative to the increasing burden of surgery and/or chemotherapy, the main therapeutics of oral carcinoma. Phytosomes are nano-vesicular systems formed by the interaction between phospholipids and phyto-active components via hydrogen bonding, exhibiting superior efficacy over pure phytocomponents in drug delivery.

METHODS

Tetrahydrocurcumin (THC)-phytosomes were prepared by thin film hydration method. After characterization, in vitro cytotoxicity, antiproliferative capacity, antioxidant potential and full apoptotic workup were paneled on oral squamous cell carcinoma (SCC4) in comparison with native THC-solution and cisplatin (3.58 µg/mL intravenous injection), as positive controls. In addition, we tested the three medications on normal oral keratinocytes and gingival fibroblasts to attest to their tissue-selectivity.

RESULTS

Successful preparation of THC-phytosomes using 1:1 molar ratio of THC to phospholipid exhibited significantly increased aqueous solubility, good colloidal properties, and complete drug release after one hour. On SCC4 cells, THC-phytosomes, at their dose-/time-dependency at ~ 60.06 µg/mL escalated cell percentages in the S-phase with 32.5 ± 6.22% increase, as well as a startling 29.69 ± 2.3% increase in apoptotic population. Depletion of the cell colonies survival to 0.29 ± 0.1% together with restraining the migratory rate by -6.4 ± 6.8% validated THC-phytosomes' antiproliferative capacity. Comparatively, the corresponding results of THC-solution and cisplatin revealed 12.9 ± 0.9% and 25.8 ± 1.1% for apoptosis and 0.9 ± 0.1% and 0.7 ± 0.08% for colony survival fraction, respectively. Furthermore, the nanoformulation exhibited the strongest immuno-positivity to caspase-3, which positively correlated with intense mitochondrial fluorescence by Mitotracker Red, suggesting its implication in the mitochondrial pathway of apoptosis, a finding further explained by the enormously high Bax and caspase-8 expression by RT-qPCR. Finally, the THC groups showed the lowest oxidative stress index, marking their highest free radical-scavenging potential among the test groups.

CONCLUSIONS

THC-phytosomes are depicted to be an efficient nanoformulation that enhanced the anticancer efficacy over the free drug counterpart and the conventional chemotherapeutic. Additionally, being selective to cancer cells and less cytotoxic to normal cells makes THC-phytosomes a potential candidate for tissue-targeted therapy.

The role of tetrahydrocurcumin in disease prevention and treatment

In recent decades, natural compounds derived from herbal medicine or dietary sources have played important roles in prevention and treatment of various diseases and have attracted more and more attention. Curcumin, extracted from the Curcumae Longae Rhizoma and widely used as food spice and coloring agent, has been proven to possess high pharmacological value. However, the pharmacological application of curcumin is limited due to its poor systemic bioavailability. As a major active metabolite of curcumin, tetrahydrocurcumin (THC) has higher bioavailability and stability than curcumin. Increasing evidence confirmed that THC had a wide range of biological activities and significant treatment effects on diseases. In this paper, we reviewed the research progress on the biological activities and therapeutic potential of THC on different diseases such as neurological disorders, metabolic syndromes, cancers, and inflammatory diseases. The extensive pharmacological effects of THC involve the modulation of various signaling transduction pathways including MAPK, JAK/STAT, NF-κB, Nrf2, PI3K/Akt/mTOR, AMPK, Wnt/β-catenin. In addition, the pharmacokinetics, drug combination and toxicology of THC were discussed, thus providing scientific basis for the safe application of THC and the development of its dietary supplements and drugs.

Synthesis, Anticancer Activity, and Molecular Docking of New 1,2,3-Triazole Linked Tetrahydrocurcumin Derivatives

Cancer is one of the deadliest diseases to humanity. There is significant progress in treating this disease, but developing some drugs that can fight this disease remains a challenge in the field of medical research. Thirteen new 1,2,3-triazole linked tetrahydrocurcumin derivatives were synthesized by click reaction, including a 1,3-dipolar cycloaddition reaction of tetrahydrocurcumin baring mono-alkyne with azides in good yields, and their in vitro anticancer activity against four cancer cell lines, including human cervical carcinoma (HeLa), human lung adenocarcinoma (A549), human hepatoma carcinoma (HepG2), and human colon carcinoma (HCT-116) were investigated using MTT(3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetraz-olium bromide) assay. The newly synthesized compounds had their structures identified using NMR HRMS and IR techniques. Some of prepared compounds, including compounds 4g and 4k, showed potent cytotoxic activity against four cancer cell lines compared to the positive control of cisplatin and tetrahydrocurcumin. Compound 4g exhibited anticancer activity with a IC50 value of 1.09 ± 0.17 μM against human colon carcinoma HCT-116 and 45.16 ± 0.92 μM against A549 cell lines compared to the positive controls of tetrahydrocurcumin and cisplatin. Moreover, further biological examination in HCT-116 cells showed that compound 4g can arrest the cell cycle at the G1 phase. A docking study revealed that the potential mechanism by which 4g exerts its anti-colon cancer effect may be through inhabiting the binding of APC-Asef. Compound 4g can be used as a promising lead for further exploration of potential anticancer agents.

The role and mechanism of TGF-β1 in the antidepressant-like effects of tetrahydrocurcumin

Astrocytes and the activation of inflammatory factors are associated with depression. Tetrahydrocurcumin (THC), the principal metabolite of natural curcumin, is renowned for its anti-inflammatory properties. In this research, we explored the impact of THC on the expression of inflammatory factors, neurotrophins, and transforming growth factor β1 (TGF-β1) in the prefrontal cortex after chronic restraint stress (CRS) in mice and in lipopolysaccharide (LPS)-induced TNC1 astrocytes. Our findings indicated that THC mitigated the anxiety and depression-like behaviours observed in CRS mice. It also influenced the expression of TGF-β1, p-SMAD3/SMAD3, sirtuin 1 (SIRT1), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), inducible nitric oxide synthase (iNOS), and tumour necrosis factor α (TNF-α). Specifically, THC augmented the expressions of TGF-β1, p-SMAD3/SMAD3, SIRT1, BDNF, and GDNF, whilst diminishing the expressions of iNOS and TNF-α in LPS-induced astrocytes. However, when pre-treated with SB431542, a TGF-β1 receptor inhibitor, it nullified the aforementioned effects of THC on astrocytes. Our results propose that THC delivers its anti-depressive effects through the activation of TGF-β1, enhancement of p-SMAD3/SMAD3 and SIRT1 expression, upregulation of BDNF and GDNF, and downregulation of iNOS and TNF-α. This research furnishes new perspectives on the anti-inflammatory mechanism that underpins the antidepressant-like impact of THC.

Augmentation of Docetaxel-Induced Cytotoxicity in Human PC-3 Androgen-Independent Prostate Cancer Cells by Combination With Four Natural Apoptosis-Inducing Anticancer Compounds

Docetaxel (DTX) is the treatment of choice for metastatic castration-resistant prostate cancer. However, developing drug resistance is a significant challenge for achieving effective therapy. This study evaluated the anticancer and synergistic effects on DTX of four natural compounds (calebin A, 3^'-hydroxypterostilbene, hispolon, and tetrahydrocurcumin) using PC-3 androgen-resistant human prostate cancer cells. We utilized the CellTiter-Glo^® luminescent cell viability assay and human PC-3 androgen-independent prostate cancer cells to determine the antiproliferative effects of the four compounds alone and combined with DTX. Cytotoxicity to normal human prostate epithelial cells was tested in parallel using normal immortalized human prostate epithelial cells (RWPE-1). We used cell imaging and quantitative caspase-3 activity to determine whether these compounds induce apoptosis. We also measured the capacity of each drug to inhibit TNF-α-induced NF-kB using a colorimetric assay. Our results showed that all four natural compounds significantly augmented the toxicity of DTX to androgen-resistant PC-3 prostate cancer cells at IC₅₀. Interestingly, when used alone, each of the four compounds had a higher cytotoxic activity to PC-3 than DTX. Mechanistically, these compounds induced apoptosis, which we confirmed by cell imaging and caspase-3 colorimetric assays. Further, when used either alone or combined with DTX, the four test compounds inhibited TNF-α-induced NF-kB production. More significantly, the cytotoxic effects on normal immortalized human prostate epithelial cells were minimal and non-significant, suggesting prostate cancer-specific effects. In conclusion, the combination of DTX with the four test compounds could effectively enhance the anti-prostate cancer activity of DTX. This combination has the added value of reducing the DTX effective concentration. We surmise that calebin A, 3^'-hydroxypterostilbene, hispolon, and tetrahydrocurcumin were all excellent drug candidates that produced significant antiproliferative activity when used alone and synergistically enhanced the anticancer effect of DTX. Further in vivo studies using animal models of prostate cancer are needed to confirm our in vitro findings.

Promising Strategy of mPTP Modulation in Cancer Therapy: An Emerging Progress and Future Insight

Cancer has been progressively a major global health concern. With this developing global concern, cancer determent is one of the most significant public health challenges of this era. To date, the scientific community undoubtedly highlights mitochondrial dysfunction as a hallmark of cancer cells. Permeabilization of the mitochondrial membranes has been implicated as the most considerable footprint in apoptosis-mediated cancer cell death. Under the condition of mitochondrial calcium overload, exclusively mediated by oxidative stress, an opening of a nonspecific channel with a well-defined diameter in mitochondrial membrane allows free exchange between the mitochondrial matrix and the extra mitochondrial cytosol of solutes and proteins up to 1.5 kDa. Such a channel/nonspecific pore is recognized as the mitochondrial permeability transition pore (mPTP). mPTP has been established for regulating apoptosis-mediated cancer cell death. It has been evident that mPTP is critically linked with the glycolytic enzyme hexokinase II to defend cellular death and reduce cytochrome c release. However, elevated mitochondrial Ca2+ loading, oxidative stress, and mitochondrial depolarization are critical factors leading to mPTP opening/activation. Although the exact mechanism underlying mPTP-mediated cell death remains elusive, mPTP-mediated apoptosis machinery has been considered as an important clamp and plays a critical role in the pathogenesis of several types of cancers. In this review, we focus on structure and regulation of the mPTP complex-mediated apoptosis mechanisms and follow with a comprehensive discussion addressing the development of novel mPTP-targeting drugs/molecules in cancer treatment.

Tetrahydrocurcumin regulates the tumor immune microenvironment to inhibit breast cancer proliferation and metastasis via the CYP1A1/NF-κB signaling pathway

The NF-κB signaling pathway is overactivated in tumor cells, and the activation of the NF-κB signaling pathway releases a large number of inflammatory factors, which enhance tumor immunosuppression and promote tumor metastasis. The cytochrome P450 (CYP450) system consists of important metabolic enzymes present in different tissues and progressive tumors, which may lead to changes in the pharmacological action of drugs in inflammatory diseases such as tumors. In this study, the anticancer effect of tetrahydrocurcumin (THC), an active metabolite of curcumin, on breast cancer cells and the underlying mechanism were investigated. Result showed that THC selectively inhibited proliferation and triggered apoptosis in breast cancer cells in a concentration- and time-dependent manner. Moreover, THC-induced cell apoptosis via a mitochondria-mediated pathway, as indicated by the upregulated ratio of Bax/Bcl-2 and reactive oxygen species (ROS) induction. In addition, THC could affect the CYP450 enzyme metabolic pathway and inhibit the expression of CYP1A1 and activation of the NF-κB pathway, thereby inhibiting the migration and invasion of breast cancer cells. Furthermore, after overexpression of CYP1A1, the inhibitory effects of THC on the proliferation, metastasis, and induction of apoptosis in breast cancer cells were weakened. The knockdown of CYP1A1 significantly enhanced the inhibitory effect of THC on the proliferation, metastasis, and apoptosis induction of breast cancer cells. Notably, THC exhibited a significant tumor growth inhibition and anti-pulmonary metastasis effect in a tumor mouse model of MCF-7 and 4T1 cells by regulating the tumor immunosuppressive microenvironment. Collectively, these results showed that TH could effectively trigger apoptosis and inhibit the migration of breast cancer cells via the CYP1A1/NF-κB signaling pathway, indicating that THC serves as a potential candidate drug for the treatment of breast cancer.

Anticancer Properties of Probiotic Saccharomyces boulardii Supernatant on Human Breast Cancer Cells

Saccharomyces boulardii, a variety of S. cerevisiae, is used as a probiotic yeast in food and drug industries. However, S. boulardii is an opportunistic pathogen, and the supernatant of this organism has recently been recommended for its health-promoting benefits. Breast cancer is the most frequent cancer disease in women worldwide. The objective of this study was to investigate the effects of S. boulardii supernatant (SBS) on cell viability, inducing apoptosis and suppression of survivin gene expression in MCF-7 and MCF-7/MX as human non-drug-resistant and multidrug-resistant breast cancer cells respectively. The IC₅₀ value of SBS against MCF-7 was calculated 1037, 542, and 543 µg/mL for 24, 48, and 72 h treatments, respectively. Also, this value against MCF-7/MX cells were measured 1242, 616, and 444 µg/mL after 24, 48, and 72 h respectively. We found that suppression of survivin gene expression should be one of the main molecular antitumor mechanisms which is contributed to apoptosis in breast cancer cells. However, anticancer activity of SBS was observed more efficient against MCF-7 than that against MCF-7/MX cells. SBS is suggested to be considered as one of the prospective anticancer drugs to treat human breast carcinoma. More investigations especially in vivo studies are strongly recommended to be implemented to characterize other antitumor mechanisms of SBS against breast carcinoma.

Tetrahydrocurcumin Chemosensitizes Breast Cancer to Albumin-Bound Paclitaxel by Enhancing SPARC Expression through Demethylation

Paclitaxel is an effective chemotherapy drug for breast cancer (BC); however, drug resistance affects long-term clinical applications. In this study, we aimed to explore whether a natural compound, tetrahydrocurcumin (THC), could sensitize BC to albumin-bound paclitaxel (ab-PTX). The in vitro sensitization effect of THC to ab-PTX was evaluated in human BC cell lines, and in vivo chemosensitivity was measured using a xenograft BC tumor model. The expression of secreted protein acidic and rich in cysteine (SPARC), a speculated protein interacting with ab-PTX, was measured. Methylation-specific polymerase chain reaction (MSP) was used to further explore whether demethylation of SPARC by THC contributed to its chemosensitivity capabilities. Higher SPARC expression was correlated with a better prognosis in patients with BC. In vitro analysis showed THC enhanced the inhibitory effect of ab-PTX on BC cells and xenograft tumors and showed significant chemosensitivity. This enhancement mainly relied on upregulating the expression of SPARC through downregulating methylation of the SPARC gene. The demethylating agent, 5-Aza-2′-deoxycytidine (5-Aza-Cdr), decreased THC's chemosensitivity effect, further confirming this molecular mechanism. THC enhanced the inhibitory effect of ab-PTX in BC by downregulating methylation of the SPARC gene. Further, upregulated SPARC increased the efficacy of ab-PTX.

Synergistic antitumor effects of polysaccharides and anthocyanins from Lycium ruthenicum Murr. on human colorectal carcinoma LoVo cells and the molecular mechanism

The antitumor effects of Lycium ruthenicum Murr. polysaccharides (LRPS) and Lycium ruthenicum Murr. anthocyanins (LRAC) were comprehensively investigated in this study. LPRS was obtained by water extraction and alcohol precipitation and further purified using diethylaminoethyl cellulose (DEAE-Cellulose) and Sephadex G-75 columns. High-performance liquid chromatography (HPLC) and Fourier transform-infrared (FT-IR) spectroscopy were used to characterize the purified LRPS. The results showed that the purified LRPS contained heteropolysaccharides, mainly composed of arabinose, galactose, and glucose with weight percentage of 41.2%, 33.6%, and 10.8%, respectively. More importantly, LRPS (500 μg/ml) and LRAC (80 μg/ml) failed to impede the proliferation of tumor cells when applied solely (48 h incubation), yet remarkable antineoplastic effects were found once they were applied altogether, since the LoVo cells, a typical human colorectal carcinoma cell line, were significantly inhibited by the mixture of LRPS (150 μg/ml) and LRAC (20 μg/ml) (LRPS&AC) in 24 h. The antineoplastic activity resulted from the combination of both LRPS and LRAC (LRPS&AC), by means of blocking the cell cycle at the G0-G1 phase and inducing LoVo cell apoptosis via reactive oxygen species (ROS)-dependent pathway. The inhibitory effects of LRPS&AC were specific to the tumor cells, without imposing on the proliferation of normal cells. Western blotting revealed that the antitumor effect was related to the mitochondria-mediated apoptosis launched by the cross-action of PI3K/Akt (phosphatidylinositol 3-kinase/protein kinase B) and JAK2/STAT3 (janus kinase 2/signal transduction and activator of transcription 3) signaling pathways. These findings for the first time reveal the synergistic antitumor effects of LRPS&AC and the related mechanisms, which enable Lycium ruthenicum Murr. to serve as a natural source to develop therapeutic reagents and functional foods with antineoplastic properties.

Synthesis and antitumor activity of new tetrahydrocurcumin derivatives via click reaction

Three new derivatives of tetrahydrocurcumin 6, 7 and 9 have been prepared as potent antitumor agents using copper(II)-catalyzed 'click chemistry'. Their structures were identified using ¹H-NMR, ¹³C-NMR and HRMS techniques. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay has been carried out to investigate the in vitro cytotoxicity against human cervical carcinoma (HeLa), human lung adenocarcinoma (A549), human hepatoma carcinoma (HepG2) and human colon carcinoma (HCT-116). Compound 6 has showed significant inhibitory activity against HCT-116 cell line with an IC₅₀ value of 17.86 μM compared to tetrahydrocurcumin (50.96 μM) and positive control etoposide (19.48 μM) while showed no inhibitory activity against NCM460 cell line. Compounds 7 showed moderate inhibitory activity compared to tetrahydrocurcumin and etoposide while compound 9 showed no obvious inhibitory activity. The results suggested further structure modifications of tetrahydrocurcumin to improve its anticancer activity.

Natural Products Targeting the Mitochondria in Cancers

There are abundant sources of anticancer drugs in nature that have a broad prospect in anticancer drug discovery. Natural compounds, with biological activities extracted from plants and marine and microbial metabolites, have significant antitumor effects, but their mechanisms are various. In addition to providing energy to cells, mitochondria are involved in processes, such as cell differentiation, cell signaling, and cell apoptosis, and they have the ability to regulate cell growth and cell cycle. Summing up recent data on how natural products regulate mitochondria is valuable for the development of anticancer drugs. This review focuses on natural products that have shown antitumor effects via regulating mitochondria. The search was done in PubMed, Web of Science, and Google Scholar databases, over a 5-year period, between 2015 and 2020, with a keyword search that focused on natural products, natural compounds, phytomedicine, Chinese medicine, antitumor, and mitochondria. Many natural products have been studied to have antitumor effects on different cells and can be further processed into useful drugs to treat cancer. In the process of searching for valuable new drugs, natural products such as terpenoids, flavonoids, saponins, alkaloids, coumarins, and quinones cover the broad space.

Development and Evaluation of Paclitaxel and Curcumin Dry Powder for Inhalation Lung Cancer Treatment

Despite the effort to develop efficient targeted drug delivery for lung cancer treatment, the outcome remains unsatisfactory with a survival rate of 15% after 5 years of diagnosis. Inhalation formulation is an ideal alternative that could ensure the direct deposition of chemotherapeutics to the lungs. However, the design of an inhalable formulation that could simultaneously achieve a high local chemotherapeutic dose to the solid tumor and exert low pulmonary toxicities is a challenge, as the presence of 10–30% of chemotherapeutics in the lung is sufficient to induce toxicity. Therefore, this study aimed to develop a simple dry powder inhalation (DPI) formulation containing a model chemotherapeutic agent (paclitaxel, PTX) and a natural antioxidant (curcumin, CUR) that acts to protect healthy lung cells from injury during direct lung delivery. The co-jet-milling of CUR and PTX resulted in formulations with suitable aerosol performance, as indicated in the high fine particle fractions (FPF) (>60%) and adequate mass median aerodynamic diameter (MMAD). The CUR/PTX combination showed a more potent cytotoxic effect against lung cancer cells. This is evident from the induction of apoptosis/necrotic cell death and G2/M cell cycle arrests in both A549 and Calu-3 cells. The increased intracellular ROS, mitochondrial depolarization and reduced ATP content in A549 and Calu-3 cells indicated that the actions of CUR and PTX were associated with mitochondrial oxidative stress. Interestingly, the presence of CUR is crucial to neutralize the cytotoxic effects of PTX against healthy cells (Beas-2B), and this is dose-dependent. This study presents a simple approach to formulating an effective DPI formulation with preferential cytotoxicity towards lung cancer.

Reductive metabolites of curcumin and their therapeutic effects

Curcumin, a secondary metabolite from the turmeric plant is one of the most promising natural products, which has been studied extensively for decades. It has demonstrated several pharmacological activities in vitro and in vivo. Various studies have indicated that the pharmacological activity of curcumin is contributed by its metabolites. The aim of this review is to present an overview of metabolic products of curcumin produced upon its reduction like di, tetra, hexa and octa-hydrocurcumin. In addition, this paper has systematically analyzed the current information regarding medicinal use of reduced metabolites of curcumin and identified the limitations which have hindered its widespread usage in the medical world. Several diverse therapeutic effects have shown to be exhibited by reduced metabolites of curcumin such as antioxidant, anti-cancerous, anti-inflammatory and immunoregulatory activities. The potential underlying molecular mechanisms of the biological activities of reduced metabolites of curcumin have also been highlighted, which may provide insight into the principle of effectiveness of curcumin.

The impact of curcumin-graphene based nanoformulation on cellular interaction and redox-activated apoptosis: An in vitro colon cancer study

Natural plants derivatives have gained enormous merits in cancer therapy applications upon formulation with nanomaterials. Curcumin, as a popular research focus has acquired such improvements surpassing its disadvantageous low bioavailability. To this point, the available research data had confirmed the importance of nanomaterial type in orienting cellular response and provoking different toxicological and death mechanisms that may range from physical membrane damage to intracellular changes. This in turn underlines the poorly studied field of nanoformulation interaction with cells as the key determinant in toxicology outcomes. In this work, curcumin-AuNPs-reduced graphene oxide nanocomposite (CAG) was implemented as a model, to study the impact on cellular membrane integrity and the possible redox changes using colon cancer in vitro cell lines (HT-29 and SW-948), representing drug-responsive and resistant subtypes. Morphological and biochemical methods of transmission electron microscopy (TEM), apoptosis assay, reactive oxygen species (ROS) and antioxidants glutathione and superoxide dismutase (GSH and SOD) levels were examined with consideration to suitable protocols and vital optimizations. TEM micrographs proved endocytic uptake with succeeding cytoplasm deposition, which unlike other nanomaterials studied previously, conserved membrane integrity allowing intracellular cytotoxic mechanism. Apoptosis was confirmed with gold-standard morphological features observed in micrographs, while redox parameters revealed a time-dependent increase in ROS accompanied with regressive GSH and SOD levels. Collectively, this work demonstrates the success of graphene as a platform for curcumin intracellular delivery and cytotoxicity, and further highlights the importance of suitable in vitro methods to be used for nanomaterial validation.

The Cancer Chemopreventive and Therapeutic Potential of Tetrahydrocurcumin

In recent decades, cancer has been one of the leading causes of death worldwide. Despite advances in understanding the molecular basis of tumorigenesis, diagnosis, and clinical therapies, the discovery and development of effective drugs is an active and vital field in cancer research. Tetrahydrocurcumin is a major curcuminoid metabolite of curcumin, naturally occurring in turmeric. The interest in tetrahydrocurcumin research is increasing because it is superior to curcumin in its solubility in water, chemical stability, bioavailability, and anti-oxidative activity. Many in vitro and in vivo studies have revealed that tetrahydrocurcumin exerts anti-cancer effects through various mechanisms, including modulation of oxidative stress, xenobiotic detoxification, inflammation, proliferation, metastasis, programmed cell death, and immunity. Despite the pharmacological similarities between tetrahydrocurcumin and curcumin, the structure of tetrahydrocurcumin determines its distinct and specific molecular mechanism, thus making it a potential candidate for the prevention and treatment of cancers. However, the utility of tetrahydrocurcumin is yet to be evaluated as only limited pharmacokinetic and oral bioavailability studies have been performed. This review summarizes research on the anti-cancer properties of tetrahydrocurcumin and describes its mechanisms of action.

Baicalein, as a Prooxidant, Triggers Mitochondrial Apoptosis in MCF-7 Human Breast Cancer Cells Through Mobilization of Intracellular Copper and Reactive Oxygen Species Generation

Background

Baicalein, a natural flavonoid derived from traditional Chinese herb Scutellaria baicalensis Georg (known as Huang Qin in Chinese), has been reported to exhibit notable antitumor activity in various cancer cells, including breast cancer. However, the detailed mechanisms underlying its induced apoptosis as a prooxidant in breast cancer cells are still unknown.

Materials and methods

In this study, we investigated the effect of endogenous copper on cytotoxic activity of baicalin against human breast cancer MCF-7 cells in vitro.

Results

Baicalein could remarkably reduce the cell viability in both dose- and time-dependent manners in MCF-7 cells but with lower cytotoxic effects on normal breast epithelial cells, MCF-10A. Such cell death could be prevented by pretreatment with Cu (I)-specific chelator neocuproine (Neo) and reactive oxygen species (ROS) scavengers. Meanwhile, baicalein could induce MCF-7 cell morphological changes, promote apoptotic cell death and increase the apoptotic cell number. Moreover, DCHF-DA staining, flow cytometry and Western blotting analyses proved that baicalein triggered the mitochondrial-dependent apoptotic pathway, as indicated by enhancement the level of intracellular ROS, disruption of mitochondrial membrane potential (ΔΨm), downregulation of anti-apoptotic protein Bcl-2, upregulation of pro-apoptotic protein Bax, release of cytochrome C and activation of caspase-9 and caspase-3 in MCF-7 cells. The pretreatment with Neo remarkably weakened these effects of baicalein. Furthermore, we confirmed that the prooxidant action of baicalein involved the direct production of hydroxyl radicals through redox recycling of copper ions.

Conclusion

These findings suggested that baicalein, acting as a prooxidant, could trigger apoptosis in MCF-7 cells occurs via the ROS-mediated intrinsic mitochondria-dependent pathway.

Tetrahydrocurcumin, Curcumin, and 5-Fluorouracil Effects on Human Esophageal Carcinoma Cells

Background:

Esophageal cancer responds poorly to traditional therapies, and novel treatments are needed. The phytochemical curcumin is a potential treatment for Esophageal Squamous Cell Carcinoma (ESCC). A curcumin metabolite, tetrahydrocurcumin (THCUR), has anti-cancer effects and greater bioavailability than curcumin.

Objective:

Evaluate THCUR as an anti-cancer agent relative to curcumin and a standard cancer drug, 5-fluorouracil (5-FU), along with treatment interactions.

Materials and Methods:

Assay cell proliferation and viability following individual and combined delivery of the compounds to three ESSC cell lines (TE-1, TE-8, and KY-5) that have different percentages of Cancer Stem Cells (CSCs).

Results:

Curcumin was significantly more effective than 5-FU in all three cell lines. It also had the greatest effect on KY-5 cells, which have the highest CSC properties, consistent with the ability of curcumin to target CSCs. Effects on ESCC cell proliferation were not detected from 40µM THCUR, a dosage above the IC50 of curcumin and 5-FU. However, THCUR at this dosage in combination with 5-FU significantly suppressed TE-1 cell proliferation, but 5-FU alone did not. As TE-1 has low CSC properties relative to the two other cell lines, it was expected to have the least resistance to chemotherapeutic treatments. Surprisingly, TE-1 was the most resistant to inhibition by 5-FU.

Conclusion:

These results and the greater stability and water solubility of THCUR than curcumin support further testing of THCUR in combination with standard treatments, particularly for chemoresistant ESCC. In contrast to concerns that curcuminoids taken by patients through diet or diet supplements might interfere with chemotherapy, suppression of 5-FU efficacy by curcumin was not observed.

Molecular targets of curcumin in breast cancer (Review)

Curcumin (diferuloylmethane), an orange‑yellow component of turmeric or curry powder, is a polyphenol natural product isolated from the rhizome of Curcuma longa. For centuries, curcumin has been used in medicinal preparations and as a food colorant. In recent years, extensive in vitro and in vivo studies have suggested that curcumin possesses activity against cancer, viral infection, arthritis, amyloid aggregation, oxidation and inflammation. Curcumin exerts anticancer effects primarily by activating apoptotic pathways in cancer cells and inhibiting pro‑cancer processes, including inflammation, angiogenesis and metastasis. Curcumin targets numerous signaling pathways associated with cancer therapy, including pathways mediated by p53, Ras, phosphatidylinositol‑3‑kinase, protein kinase B, Wnt‑β catenin and mammalian target of rapamycin. Clinical studies have demonstrated that curcumin alone or combined with other drugs exhibits promising anticancer activity in patients with breast cancer without adverse effects. In the present review, the chemistry and bioavailability of curcumin and its molecular targets in breast cancer are discussed. Future research directions are discussed to further understand this promising natural product.

Antitumor effect and molecular mechanism of antioxidant polysaccharides from Salvia miltiorrhiza Bunge in human colorectal carcinoma LoVo cells

Salvia miltiorrhiza Bunge polysaccharides (SMP) was comprehensively investigated in this study. The polysaccharides were extracted by the method of water boiling and ethanol precipitation with high purity. The monosaccharide composition of SMP was characterized using the established HPLC-UV protocol with PMP precolumn derivatization, and the results indicate that the polysaccharides are mainly composed of d-galactose (Gal), d-glucose (Glc) and d-galacturonic acid (GalUA), and their mole percentages are 64.5%, 31.1% and 4.4%, respectively. In addition, the antioxidant potential of SMP was evaluated in terms of reducing power, scavenging ability against DPPH, superoxide and hydroxyl free radicals. The results indicate that polysaccharides from S. miltiorrhiza Bunge possess versatile antioxidant activities in a dose-dependent manner. Furthermore, SMP is observed with high inhibition ratio against LoVo cells (typical tumor cells) in both dose- and time-dependent manners. FCM analysis demonstrates that SMP is able to induce apoptosis of LoVo cells, arrest the cell cycle at S phase, as well as elevate the intracellular reactive oxygen pressure. These findings for the first time reveal the potential anti-tumor mechanism of SMP, suggesting that SMP may serve a natural anticancer agent with lower cost and cytotoxicity, as well as a bioactive factor for functional food development.

Tetrahydrocurcumin induces mesenchymal-epithelial transition and suppresses angiogenesis by targeting HIF-1α and autophagy in human osteosarcoma

Human osteosarcoma is considered a malignant tumor with poor prognosis that readily metastasizes. Tetrahydrocurcumin (THC) has been reported to have anti-tumor activity in numerous tumors. In addition, hypoxia-inducible factor-1α (HIF-1α) has been demonstrated to be associated with tumor metastasis by regulating epithelial-mesenchymal transition (EMT). However, the role of THC in osteosarcoma remains uncertain. Therefore, this study aimed to elucidate the potential mechanisms. We found that THC significantly reduced the growth of osteosarcoma cells and suppressed migration and invasion, as tested in a nude mouse lung metastasis model. Additionally, the mesenchymal-epithelial transition (MET) process was facilitated by THC. Mechanistically, our study showed that HIF-1α had a pivotal role in the anti-metastatic effect of THC. Importantly, HIF-1α expression was downregulated by THC by inhibiting Akt/mTOR and p38 MAPK pathways. Moreover, THC exhibited a remarkable inhibitory effect on HIF-1α expression and angiogenesis under hypoxic conditions. Furthermore, THC activated autophagy and induced MET and suppressed angiogenesis in a HIF-1α-related manner. Taken together, our findings suggest that THC suppresses metastasis and invasion and this may be associated with HIF-1α and autophagy, which would potentially provide therapeutic strategies for human osteosarcoma.

Curcumin induced autophagy anticancer effects on human lung adenocarcinoma cell line A549

To investigate the anticancer effects of curcumin-induced autophagy and its effects on the human lung adenocarcinoma A549 cell line, inverted phase contrast microscopy was used to observe alterations to the cytomorphology of cells. An MTT assay was used to measure cell viability. Autophagy was detected using acridine orange (AO) staining and 3-methyladenine (3-MA) was used as an autophagy-specific inhibitor. Dose- and time-dependent A549 cell viability inhibition was observed following curcumin treatment. A dose-dependent increase in the red fluorescent structures in A549 cells was identified following curcumin treatment for 48 h through AO staining. In addition, the activation of autophagy was determined through changes in the number of autophagic vesicles (AVs; fluorescent particles) infected with monodansylcadaverine (MDC). The fluorescence intensity and density of AVs in the curcumin-treated groups were higher at 48 h compared with the control group. Finally, the MTT assay demonstrated that the survival rates of the curcumin-treated cells were increased when pretreated with 3-MA for 3 h, indicating that the inhibitory effect of curcumin on A549 cells is reduced following the inhibition of autophagy. Furthermore, AO and MDC staining confirmed that 3-MA does inhibit the induction of autophagy. Thus, it was hypothesized that the induction of autophagy is partially involved in the reduction of cell viability observed following curcumin treatment. The anticancer effects of curcumin on A549 cells can be reduced using autophagy inhibitors. This suggests a possible cancer therapeutic application of curcumin through the activation of autophagy. These findings have improved the understanding of the mechanism underlying the anticancer property of curcumin.

Effect of PGC-1α overexpression or silencing on mitochondrial apoptosis of goat luteinized granulosa cells

During goat follicular development, abnormal expression of peroxisome proliferator- activated receptor gamma coactivator-1 alpha (PGC-1α) in granulosa cells (GCs) may contribute to follicular atresia with unknown regulatory mechanisms. In this study, we investigate the effect of ectopic expression or interference of PGC-1α on cell apoptosis of goat first passage granulosa cells (FGCs) in vitro. The results indicate that PGC-1α silencing by short hairpin RNA (shRNA) in goat FGCs significantly reduced mitochondrial DNA (mtDNA) copy number (P < 0.05), changed mitochondria ultrastructure, and induced cell apoptosis (P < 0.05). The transcription and translation levels of the apoptosis-related genes BCL-2-associated X protein (BAX), caspase 3, and caspase 9 were significantly up-regulated (P < 0.05, respectively). Moreover, the ratio of BAX/B-cell lymphoma 2 (BCL-2) was reduced (P < 0.05), and the release of cytochrome c (cyt c) and lactate dehydrogenase (LDH) was significantly enhanced (P < 0.05, respectively) in PGC-1α interference goat FGCs. Furthermore, the expression of anti-oxidative related genes superoxide dismutase 2 (SOD2), glutathione peroxidase (GPx) and catalase (CAT) was down-regulated (P < 0.05, respectively) and the activity of glutathione/glutathione disulfide (GSH/GSSG) was inhibited (P < 0.05). While enforced expression of PGC-1α increased the levels of genes involved in the regulation of mitochondrial function and biogenesis, and enhanced the anti-oxidative and anti-apoptosis capacity. Taken together, our results reveal that lack of PGC-1α may lead to mitochondrial dysfunction and disrupt the cellular redox balance, thus resulting in goat GCs apoptosis through the mitochondria-dependent apoptotic pathway.